If you use USD and want Yen you don't necessarily have to exchange them. You can start working for Yen. It's the same with bitcoins. You don't have to buy them you can just start services to earn them. I like it better because then you don't have to give out your ID to some online company!
It's hard to earn bitcoins because of its huge value in marketing and advertising industry and also the best currency in the world and also the world market day by day and I have paid the world